Valve assemblies are used within vehicles and other apparatuses and assemblies to control the flow of fluids, gasses, and/or other materials between various interconnected and/or communicating portions or chambers which are respectively contained and/or resident within these vehicles, apparatuses, and assemblies.
One type of valve assembly, known as an "air bleed" check valve assembly, is typically disposed within a hydraulic circuit (e.g. within the hydraulic circuit of a vehicle clutch assembly), and operatively allows air or gas to pass from a portion of the hydraulic circuit and through the valve assembly, while substantially and concomitantly preventing hydraulic fluid from escaping and/or exiting from the hydraulic circuit and from passing through the valve assembly.
This type of valve assembly typically includes a "check ball" or member which is contained within a channel or slot. The channel includes an aperture or passage through which the gas or air, escaping and/or exiting from a portion of the hydraulic circuit, may pass. The aperture is substantially surrounded by a valve seat. The ball member is movable between a first position in which the ball member resides upon the valve seat, and a second position in which the ball member does not reside on the seat (e.g., in which the ball member is remotely positioned from the ball seat), thereby allowing air or gas to pass through the aperture, to be received within a certain portion of the valve assembly, and to be expelled from the valve assembly. The selective movement of the ball member allows gas or air to be expelled and/or discharged from a portion of the hydraulic circuit and to be communicatively transferred and/or moved through the valve assembly, while substantially preventing hydraulic fluid from being expelled from the circuit. Particularly, the flow of the relatively high density hydraulic fluid into the valve assembly causes the ball member to move from the second position to the first position, thereby covering the aperture and preventing the hydraulic fluid from passing through the aperture and through the valve assembly.
While this prior type of valve assembly is relatively effective to operatively expel/discharge and/or communicatively transfer gas or air from and/or by and between portions of a hydraulic circuit, it suffers from some drawbacks which adversely effect its performance.
For example and without limitation, when air or gas is passed through this prior type of valve assembly, the pressure on the other side or portion of the valve assembly (the side or portion which receives the "passed" or discharged air or gas) is often increased. This increase in pressure typically results in and/or causes air to flow or "bleed" back through the valve assembly and into the portion of the hydraulic circuit from which the air or gas had been expelled. This "back flow" or "drain back" of air or gas into the hydraulic circuit causes the circuit to have inconsistent system operating and response characteristics and to be "unstable". For example and without limitation, the amount of time required to achieve and maintain a certain pressure within the circuit varies, is not readily ascertainable, and is undesirably increased due to this back flow of air or gas into the circuit.
There is therefore a need for a new and improved valve assembly for use in combination with a hydraulic circuit or device; which allows gas or air to exit from the hydraulic circuit and to pass through the valve assembly while substantially preventing hydraulic fluid from exiting the hydraulic circuit; which substantially prevents the previously expelled air and/or gas from flowing back into the portion of the hydraulic circuit from which the air or gas has been expelled; and which substantially improves the overall stability and operating characteristics of the hydraulic circuit.